1. The Field of the Invention
The present invention relates to airbag protection systems in motor vehicles. More specifically, the invention relates to a retainer for a tether of a curtain airbag.
2. Technical Background
Inflatable airbags are well accepted for use in motor vehicles and have been credited with preventing numerous deaths and injuries. In fact, the inclusion of inflatable safety restraint devices, or airbags, is now a legal requirement for many new vehicles. Airbags are typically installed in the steering wheel and in the dashboard of a vehicle. In the event of an accident, an accelerometer within the vehicle measures the abnormal deceleration and triggers the expulsion of rapidly expanding gases from an inflator. The expanding gases fill the airbags, which immediately inflate in front of the driver and passenger to protect them from impact against the windshield. Side impact airbags, known as curtain airbags, have also been developed in response to the need for protection from impacts in a lateral direction, or against the side of the vehicle.
Recently, airbag technology has advanced such that curtain airbags are now enlisted to provide roll-over protection as well as side impact protection. During a roll-over accident, occupants can be jostled around considerably. Consequently, the occupant may be ejected from the vehicle. Alternatively, a head or limb of an occupant may extend outside the vehicle during the roll-over. “Occupant excursion” during roll-overs is a common cause of automotive fatality, particularly in the case of vehicle occupants that are not wearing a seat belt during the roll-over.
Conventional curtain airbags, generally unfold or unroll downward to inflate beside a person to prevent the person from hitting the door or window during lateral impact. Since a vehicle occupant may be leaning forward, reclined in the seat, or at any position between, such airbags are often long enough to cover the whole interior side of a vehicle, protecting occupants in both the front and rear passenger compartments.
To provide side impact and roll-over protection, curtain airbags are sized to hold large volumes of inflation gas and descend below the window sill. In addition, the curtain airbag typically includes a tether connected to the bottom corner at each end. The tether is anchored to the bottom corner of the front and back roof pillars of the vehicle. The tether provides tension and support of the curtain airbag to prevent occupant excursion. However, due to the contour of the roof and pillars, often, the side of the vehicle is a trapezoid shape and the curtain airbag is generally rectangular shaped. This leaves a triangular area exposed in the lower corners. Typically, the tether is a single strap which does not close the triangular area. During a roll-over accident, an occupant's limb may extend through the unprotected triangular area resulting in serious injury.
To protect against limb excursion, the conventional strap tether may be replaced by a sail tether. Generally, the sail tether is a single layer of material similar to that used for the airbag curtain. The sail tether is shaped to fit the triangular area. The sail tether may be sewn or similarly attached to the vertical edge of the airbag curtain. The sail tether is rolled or folded with the airbag curtain during assembly. Thus, rather than a substantially two-dimensional airbag tether, a three dimensional sail tether roll is to be stored and concealed until the curtain airbag activates.
Typically, a single strap or rolled sail tether is stored and retained lengthwise within the A-pillar and the C or D-pillar of a vehicle. The area within the pillar for storing and retaining the tether is referred to herein as a “package”. The package is an area between the frame of the pillar and the ornamental trim secured to the frame. The tether is stored until the curtain airbag is activated. The inflating curtain airbag pulls the tether out from the package and down toward the window sill.
The tether is retained to ensure that the tether stays in an operable position during the expected life of the vehicle, particularly if pillar trim needs to be removed for a repair after sale of the vehicle. In addition, retaining the tether reduces a vehicle manufacture's liability from loose items projecting around the passenger compartment during an accident.
Conventionally, the tether is retained within the package by an extrusion which runs the length of the pillar. The extrusion serves as a housing for the tether. The extrusion is made by extruding material such as hard plastic through a die.
Generally, the extrusion includes an opening extending along the length for receiving the tether. A press-lock fastener is pressed into the opening to engage walls of the extrusion to close the opening. The press-lock fastener may be attached or attachable to the trim. The extrusion is secured to the frame of the pillar when the inflatable curtain airbag module is installed in a vehicle. Conventional tether retainers such as extrusions have been hindered by a number of problems.
One problem is that conventional tether retainers, particularly those used with sail tethers, have prevented a vehicle manufacturer from complying with U.S. federal regulations. These regulations prevent a manufacturer from the selling the vehicle in the U.S., or may require a recall, if failure to meet the regulations is discovered after a vehicle sale.
Generally, vehicle manufacturers favor both styling and aesthetic appeal of a vehicle design and compliance with safety requirements imposed by the government. However, where these two interests collide, solutions should be found which most favorably fulfill both interests.
Recent safety requirements contained in the Federal Motor Vehicle Safety Standards (FMVSS), particularly standard 201, set out performance requirements for providing head impact protection for occupants. As part of the requirements, a manufacturer should provide protection in the A-pillar for an occupant during a low speed accident. Generally, these are accidents in which the curtain airbag may not be deployed but the occupant may suffer significant injury. Specifically, the A-pillar should be designed to absorb a certain amount of energy from the impact. Typically, this is done by installing foam, or other yielding energy absorbing material (referred to herein as countermeasures) into the trim which covers the A-pillar.
Styling designs for the vehicles include the maximum shape and size of the A-pillars as well as the shape, size, texture, and color of the trim attached to the pillars. The minimum shape and size is generally dictated by the structural requirements for the A-pillars. In addition, styling designs aid in marketing the vehicle.
The manufacturer prefers to comply with both styling and safety requirements. These requirements generally dictate the size of the package for the curtain airbag tether and retainer. Use of three dimensional sail tether rolls including conventional extrusion tether retainers requires a larger package. If the package is larger, less countermeasure may be used which may cause the vehicle to fail the safety standard. If the additional countermeasure material is included, the trim shape may need to be changed which modifies the styling.
Furthermore, conventional styling requirements may require an A-pillar having a curved contour. Conventional extrusion tether retainers are rigid and straight. Therefore, the conventional extrusion is inoperable with contoured A-pillars.
In addition, because space in the A-pillar is minimal, generally a first extrusion is designed specifically to fit a right A-pillar and another for the left A-pillar. The specific design for right and left A-pillars is due to the curve of the pillar and position of trim fasteners, fastener bolt holes, and other A-pillar features. Furthermore, the left and right extrusions typically may only be installed in one way. While the extrusion are capable of being installed on the wrong sides, doing so may cause the curtain airbag to fail to deploy properly.
Using two slightly different extrusions increases tooling costs for the parts. The two similar extrusions may also be easily confused by a worker installing them. Improper installation may require an expensive recall or additional inspection processes.
Another problem is the impact on workers securing the tether within the extrusion. Typically, joining the press-lock fastener to the opening is slow and labor intensive. The small size of the extrusion and tight fit of the press-lock fastener require workers to pinch and press with their hands and fingers. Repeatedly joining high numbers of press-lock fasteners and extrusions may lead to repetitive stress injuries including carpal tunnel syndrome.
Accordingly, it would be an advancement in the art to provide an airbag tether retainer which fits within a smaller package size such that vehicle safety and styling requirements for vehicle pillars may be readily accommodated. It would be a further advancement to provide an airbag tether retainer that is flexible to conform to curves and other features of vehicle pillars including A-pillars. It would be another advancement in the art to provide an airbag tether retainer that is less expensive to fabricate than conventional airbag tether retainers. Additionally, it would be an advancement to provide an airbag tether retainer of a single design that may be installed on either the right or left side pillars of a vehicle. It would be another advancement in the art to provide an airbag tether retainer which places less repetitive stress and strain on a worker securing the airbag tether retainer to an airbag tether. The present invention provides these advancements in a novel and useful way.